Question

if y varies directly as x and y=35 when x=7,find y when x=11

Answer 1

The statement y varies directly as x can be written as \[y=kx\]where k is a constant of proportionality. You are given the relationship that y=35 when x=7. You can use this to find the value for k. Substitute 7 for x and 35 for y and solve for k.
\[35=7k\]\[k=5\]Now that we know what k is, we can substitute 11 for x and 5 for k to find the value of y.\[y=(5)(11)\]\[y=55\]So y=55 when x=11